Fail-safe safety system to detect and annunciate fractured running rails in electrically propelled transit systems

ABSTRACT

The present invention relates to a fail-safe safety system to detect and annunciate fractured running rails in electrically propelled transit systems using catenaries or third rail power contactors without the need to induce block by block communication signals currently required by existing systems for detecting occupancy and broken running rails. In addition, unlike existing systems, the present invention is fail-safe, fault tolerant, and self annunciating in that if any component, or connection, of the system fail, or is out of tolerance, it is immediately communicated to a central location. Further, also unlike existing systems, the present invention does not require, or interfere with, automatic train controls because it uses the propulsion power bus, itself fail-safe, as an independent means of communication without additional wiring.

CROSS-REFERENCE TO RELATED APPLICATIONS References Cited

U.S. Patent Documents 6,972,687 December, 2005 Marshall, et al. 340/686.1 6,655,639 December, 2003 Grappone. 246/120 5,680,054 October, 1997 Gauthier. 324/713 4,886,226 December, 1989 Frielinghaus 246/121 4,728,063 March, 1988 Petit, et al. 246/34R 4,306,694 December, 1981 Kuhn 246/125 4,117,529 September, 1978 Stark, Ehrlich 361/182

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a fail-safe safety system to detect and annunciate fractured running rails in electrically propelled transit systems without the need to induce block by block communication signals, using block transmitters and receivers, currently required by existing systems for detecting occupancy, transmitting speed commands, and detecting broken running rails. Additionally, unlike existing systems, the present invention can detect running rail fractures that are not completely broken and bidirectionally communicate control operating parameters and the location of the fracture over existing propulsion power lines.

2. Discussion of Background

With the advent of Computer Based Train Control (CBTC) systems that use moving blocks existing fixed block rapid transit systems operating on running rails such as the Bay Area's Rapid Transit Districts, BART, and Municipal Railway, MUNI, in San Francisco Calif. it is imperative that we develop a system to detect and annunciate broken or fractured running rails.

It has been, and still is, an ongoing problem detecting, and annunciating, a fractured running rail with CBTC systems because in these systems there are no, as in fixed block systems, individual block signaling currents that detect and annunciate a broken running rail.

Further exasperating the problem is the present lack of communication lines from wayside to communicate fractured running rail information to a central location that can control train movement. These leading areas of concern, coupled with projected costs and time to implement a solution, have caused transit agencies to avoid upgrading their fixed block systems to CBTC that can, and would, substantially increase passenger throughput and reduce commute times.

Because the primary concern of any mass transit system is to avoid conflict between safety and the transit systems desire to move the maximum number of passengers from point A to point B, in the shortest period of time, with the highest degree of operating reliability it is imperative that any proposed system be fail-safe and in concord with these seemingly incompatible, opposing, and contradictory objectives.

Today the vast majority of existing rapid transit systems regulate the speed of trains by using duel mode block by block track signaling and occupancy detecting systems built into the running rail tracks and controlled by wayside Automatic Train Control (ATC) systems. These systems transmit predetermined speed commands to the trains, as a function of track occupancy, grade, and position, to the front of the train in essence pulling it along. Train detection, or detection and annunciation of broken running rails, are both accomplished by removing these speed commands using either the train's wheels to short out, or by a broken running rail, that in essence removes the signals normally received by occupancy detection track receivers that are physically located behind the train—indicating an occupancy.

There have been numerous patents to detect and annunciate fractured running rails most notably by Grappone, U.S. Pat. No. 6,655,639, Gauthier U.S. Pat. No. 5,680,054, Frielinghaus, U.S. Pat. No. 4,886,226, Petit, et al. U.S. Pat. No. 4,728,063, Kuhn, U.S. Pat. No. 4,306,694, and Stark et al. U.S. Pat. No. 4,117,529. Virtually all of these induce signals into the running rails, can only detect completely broken rails, and use a unidirectional hard wired, or radio frequency, communications link that only transmits information and is, more importantly, not fail-safe.

In order to resolve these concerns in a timely and cost-effective manner a solution must be found that: is compatible with the existing system, does not require inducing signals into the running rails, can detect fractures in rails that are not complete fractures, has bidirectional communications that can communicate over existing propulsion power lines and above all is fail-safe without sacrificing operating reliability and throughput—all of which this present invention, as follows, uniquely satisfies.

BRIEF SUMMARY OF THE INVENTION

Accordingly the major factors associated with the detection and annunciation of fractured rails, already briefly recited, the present invention provides a simple means for the long-felt need to detect and annunciate fractures in running rails of CBTC systems in a fail-safe manner. The core of the invention is detecting an unbalance in propulsion currents in the ground returns provided by the two running rails with, or without, automatic train controls, and communicate this imbalance in a fail-safe manner to a central location—indicating a fracture. The invention measures and compares electrical propulsion currents in existing running rail returns and communicates this information, in a fail-safe manner, over existing propulsion power lines using commercially available power line communications (PLC) equipment to a central controller location.

It is normal operating practice in transit systems operating electrically propelled transit vehicles to physically partition multiple sections of tracks to allocate a multiplicity of power sources. This is so traction power requirements are distributed among these sources and in addition to provide for alternate, and/or redundant sources of power, in the advent of failure of any one power source. By virtue of this physical partitioning detection of an unbalance in leakage or running rail traction power, such as a fracture in a running rail, a physical location can be determined either on site or at a central controller location.

Bi-directional communication from wayside to a central location in a fail-safe manner is uniquely accomplished using proven and commercially available Power Line Communications (PLC) technology communicating over propulsion power lines. By virtue of this no additional communication cabling is required and the exact zone location of the fractured rail can be communicated.

In the interest of brevity, and not to obfuscate the essence of this application, features of the invention that are readily apparent to those skilled in the art have not been delineated in detail here but are mentioned for those without that expertise. Implicit, owing to the bidirectional nature of the communications controllers and power line communicators operating parameters of the system are easily reconfigured and resolution of detection within zones can be increased by adding more transducers, communications controllers and power line communications. In addition, the transit vehicle itself may receive and communicate with central and wayside by simply having on board power line communications.

Other features, and their advantages, of this system will be apparent to those skilled in the art of running rail fracture detection and annunciation from a careful reading of the Detailed Description of Preferred Embodiments accompanied by the following drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

In the drawings,

FIG. 1 is a block diagram of the wayside fail-safe safety system to detect and annunciate fractured running rails in electrically propelled transit systems.

FIG. 2 is a block diagram of the central control fail-safe safety system to detect and annunciate fractured running rails in electrically propelled transit systems.

FIG. 3 is a block diagram of the central control fail-safe safety display and annunciation system to detect and annunciate fractured running rails in electrically propelled transit systems.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a fail-safe safety system to detect and annunciate fractured running rails in electrically propelled transit systems. The system is designed as a fail-safe, fault tolerant, and self annunciating system in that if any component, or connection, of the system fails, or is out of tolerance, it is immediately communicated to a central location. Additionally, unlike existing systems, the present invention does not require, or interfere with, automatic train controls and uses the propulsion power bus, itself fail-safe, as a means of bidirectional communication without additional cabling.

FIG. 1 is a wayside block diagram of the preferred embodiment of the system showing propulsion power substation 900 supplying power by propulsion power source bus 800 to transit propulsion power bus 700 consisting of third rail or catenary's with propulsion power return bus 950 providing the returns for propulsion currents I₁+I₂ in running rails 250 and 350 respectively.

As shown current transducer 100 detects running rail current I₁ and current transducer 200 detects running rail current I₂ of zone 1—of a multiple (N zone) system. Note: that in normal operation, without a fracture, 600 in zone 1, running rail current I₁ and running rail current I₂ are, within a known margin of error, equal. The magnitudes of I₁ and I₂ are sent to the bidirectional communications controller 300 and communicated to Power Line Communications (PLC) device 400.

Central control, 500, physically located at the train control center polls power line communicators 400, processes and interfaces with train control computers and displays. Whenever an unbalance, or a complete absence, between running rail track currents I₁ or I₂ exists central control electronics alarms and displays this information on train control displays.

FIG. 2 is a module wide illustration of FIG. 1, 500, block diagram of the central control fail-safe safety system showing propulsion power bus 700 connected to bidirectional power line communications module 400, communicating with central communications controller, 325, in turn communicating with central computer, 450, in turn communications with display, 550.

Under software, and operator, control central computer, 450, queries central communications controller, 325, that in turn queries power line communications, 400, for the integrity of the running rails as shown in FIG. 1, 250 and 350.

As shown in FIG. 2, central computer, 450, processes signals received from central communications controller, 325, and power line communications module, 300, that are received from FIG. 1 power line communications modules 400 processing the signals received from wayside electronics 100,200, 300 and 400 modules that determines the integrity of running rails 250 and 300 in FIG. 1.

In turn this information is translated into a pictorial visual presentation by display, 550, of FIG. 3. FIG. 3, 580, displays a physical location of the area of concern of running rails 250 and 350 with fracture 600 being indicated on running rail 350 by 590 indicting a rail fracture between Mile Post (MP) 2.84 and MP 2.26. In addition there is an audible and visual indication by 575 irrespective of the visual display 550.

It is readily apparent to those skilled in the art of detection and annunciation of fractured running rails, especially in electrically propelled rapid transit systems, from reading the foregoing that many substitutions and modifications, including but not limited to, using transit running rails to monitor propulsion currents and propulsion power lines to communicate this information may be made to the preferred embodiments described without departing from the spirit and scope of the present invention. 

1. A system for detecting and annunciating fractured running rails in electrically propelled transit systems with said system using a difference in propulsion currents in running rails to detect fractures and comprised of transducers, communication controllers, power line communication devices, central communication controllers, computers, displays, and annunciators.
 2. The system as recited in claim 1, further comprising central control processing with data decoding devices comprised of computer electronics and software algorithms as a means of decoding and displaying data, sending commands from, and or to, an on board automatic train control system or wayside communications controller for the purpose of detecting and annunciating fractured running rails.
 3. The system as recited in claim 1, wherein said communications controller being comprised of computer electronics and software algorithms as a means of formatting, selecting, and communicating with said power line communication devices, and said central control processing and displays, to communicate a fracture in a running rail to wayside transducers, central control and/or on board train control electronics.
 4. The system as recited in claim 1, further comprising electromagnetic or current transducers themselves comprised of electronics or other transducers whose purpose is to communicate a fracture in running rails by way of a communications controller and power line communications device to central control processing.
 5. The device as recited in claim 1, wherein said power line communication transceivers being comprised of electronic transmitter-receiver equipment necessary to communicate a fracture in running rail to central control processing and/or on board train controls with a high degree of noise rejection and reliability.
 6. The central control processing with displays as recited in claim 1, further comprised of Liquid Crystal, Cathode Ray Tubes, Plasma or electro-fluorescent displays and annunciators communicating with central control computers.
 7. The displays as recited in claim 1, wherein said displays graphically display and pictorially annunciate the location and criticality of fractures in running rails.
 8. The displays as recited in claim 1, wherein said displays graphically display the location of a suspected fracture between mile posts and pictorially represent and display the fracture.
 9. The displays as recited in claim 1, wherein said displays graphically display the location of a suspected fracture by indicating which operating line of the transit system the suspected fracture is located.
 10. The displays as recited in claim 1, wherein said displays graphically display the entire transit system, mile posts, and physical transit line location of the suspected fracture.
 11. The system as recited in claim 1, further comprising fail-safe hardware and software design for the purpose of detecting and annunciating fractured running rails in a fail-safe manner.
 12. The system as recited in claim 1, further comprising bidirectional communication controllers.
 13. The system as recited in claim 1, further comprising bidirectional power line communication devices 